Such a method is in particular implemented in hydrocarbon exploitation solutions passing through an expanse of water, for example comprising a rigid structure fixed on the sea bottom or a floating structure such as a naval surface support, a semi-submersible platform, a floating riser, or a ship.
The flexible line to be connected on the structure is for example a flexible rising fluid transport pipe, also referred to as a riser. “Flexible pipes” refers to those described in the normative documents published by the American Petroleum Institute (API), API 17J and API RP 17 B and well known by those skilled in the art. More generally, the flexible line may be a composite bundle, a set of umbilicals or electrical cables.
The method of the aforementioned type is used during the installation and connection of the flexible line on the surface structure.
To that end, to reduce the risks of damage to the structure and the flexible line, it is known to submerge the flexible line in the expanse of water below the surface structure, and to raise it up to the connection area situated on the surface structure using a winch. Such a connection is referred to as a “pull-in”.
The flexible line is guided on the structure by inserting it through a hollow rigid tube secured to the structure, oriented vertically, which constitutes a protective sleeve. The hollow tube is for example of the “I-tube” or “J-tube” type.
At the upper output of the tube, the flexible line is connected on the surface installation.
To avoid deteriorating the flexible line, in particular under the effect of the agitation of the water that may cause it to come into contact with the structure, it is known to mount a bend limiter, engaged around the flexible line, capable of locally imposing a bend radius greater than the minimum bend radius that the flexible line may occupy.
In the rest of the text, “bend limiter” refers to bend limiters for example made up of hinged rigid elements called “vertebrae”, and limiters for example made up of multiple blocks of plastic material, as well as combinations of those elements.
A bend limiter is for example positioned around the flexible line in the vicinity of its upper end to cooperate with the hollow tube during the insertion of the flexible line into the tube.
To that end, first, the bend limiter and the flexible line are moved jointly toward the lower end of the hollow tube until the limiter is partially inserted into the hollow tube. Then, secondly, the flexible line is moved upward relative to the bend limiter to raise it through the hollow tube in order for it to be connected on the surface structure.
During the second phase, the bend limiter is kept immobile in translation in the hollow tube by embedding and/or fastening using gripping collars.
WO 98/23845 describes a method using a single winch to pull the flexible line and the bend limiter while temporarily securing the bend limiter to the flexible line using a frangible pin.
During the raising of the bend limiter toward the lower end of the hollow tube, the bend limiter and the flexible line move jointly. The bend limiter is then fastened to the lower end of the tube. Sufficient upward traction is then applied on the flexible line so as to break the frangible pin to allow the upward movement of the flexible line relative to the bend limiter.
Such a method is not fully satisfactory. In fact, to allow the release of the flexible line relative to the bend limiter, it is necessary to move the line locally relative to the bend limiter to cause the frangible pins to break. Such movement results from the implementation of an upward traction force on the flexible line. Such a force may deteriorate the pipe.
Furthermore, the method is complex and requires great reliability of the mechanical parts inserted between the flexible line and the bend limiter.